Is a vapor barrier mandatory with above-rafter insulation?

  • Erstellt am 2016-05-11 06:16:28

S.Brandt

2016-05-11 06:16:28
  • #1
Hello,

our roofing company told us that they want to install a Delta-Sd Flexx renovation vapor retarder under the insulation on top of the rafters instead of a vapor barrier. They say this is better.

This concerns a new building where we want to leave the roof structure visible from the inside. The construction is planned as follows:

1.) Rafters 2.) 19mm visible boarding (spruce wood) 3.) Delta-Sd Flexx renovation vapor retarder (?????) 4.) Bauder PUR insulation on top of the rafters 180mm WLG026 coated with mineral fleece 5,6,7) Battens / roofing

He said that if I insisted, he would also install a PE foil instead of the Delta vapor retarder.

Does anyone have experience with what is the most sensible now? - I can’t really do more than rely on him as an expert. But one is still allowed to have doubts :-)

Many thanks!
 

S.Brandt

2016-05-11 07:06:43
  • #2
oh yes, on top of the insulation, under the battens, there is still a vapor-permeable underlay membrane
 
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